Photo credit: Gardenvity
A water-filled wood-fired hot tub is a heavy unit on its own, let alone when occupied by its users (approximately 2,000 kilograms). When buying a hot tub, you have to think about also setting up a suitable base for it to sit on before it gets delivered. There are quite a few options to choose from, but one thing is clear – don’t place it directly on your lawn.
So, what makes the best base for a wood-fired hot tub? What are the most effective as well as the least expensive options? How much space do you need to plan, and what electricity installation is necessary for the power supply?
Each seller will advise you on the above questions with slight variations. In this article dealing with the most popular questions people ask, we’re going to combine the information available online with what we know from the practical use of wood-fired hot tubs to provide a summarised review. Here we go!
Choose the right location first
Survey your property first to pick the best location for your wood-fired spa. Make sure that the ground is level and firm enough to serve as a foundation for a unit that weighs upwards of 1,500 kilograms when filled with water! One to two-seater units or all-wood and off-the-grid models will be closer to a weight margin of 1.5 tonnes, whereas bigger models with spa systems and water filters can go up to twice that figure. The total weight should be displayed on the product pages on most brands’ e-stores.
Keep in mind that your wood burner will produce some smoke, and sometimes flying hot ash. That’s why a minimum of 3 metres’ distance from any objects must be adhered to. Chimney extensions are always a good idea to spread the escaping smoke as high as possible.
Please remain considerate of your neighbours and, if at all possible, keep the hot tub as far away as you can from their windows. Even if your neighbours don’t complain about your garden parties, they might feel uneasy about being unable to open their windows or hang out the laundry on a sunny day when the water in your hot tub is heating up.
Can a wood-fired hot tub be installed under a roof?
For their own peace of mind, most wood-fired hot tub manufacturers will allow unit installation under a roof to be completed only by authorised safety specialists or wood-fired hot tub installers. There are strict requirements for placing a wood-burning unit in pergolas, gazebos, roofed terraces or other structures. Generally, a wood-fired hot tub is intended for outdoor use only. Even sinking it into the decking is permitted only by a select few manufacturers.
How far should a wood-fired hot tub be located from the house?
It is essential to install your wood-fired hot tub as far away from any flammable objects or buildings as possible, but no less than 1-1.5 metres away. Take note also that the chimney top must not be closer than within 3 metres of any nearby object. Many specialists recommend chimney extensions to raise its height. Be mindful of where you drain the water too, and keep in mind that fire risk is not the only concern to consider when picking a spot for your spa.
How much space is needed around a hot tub?
It can prove to be very helpful to have enough space for you and other people to move around the hot tub for doing maintenance work, for example. The general recommendation is to leave at least 0.5-1 metre around all sides of the unit for easy access. Of course, the sides of the hot tub where the steps are located for getting in and out, and where the wood-burning stove is located, will need even more space around them for convenient access.
Prepare the base
The more solid the surface on which your hot tub is going to sit, the better. A concrete pad or stone pavement is ideal, and wooden or PVC deckings are similarly fabulous for the purpose and will provide an attractive look. Make sure to check with hot tub manufacturers to see whether they offer hot tub designs that can be sunk into the decking, and you should refuse if your chosen model cannot be recessed in the deck.
A major no-no when it comes to hot tub placement is to put it directly onto your lawn. This is because the vegetation underneath the unit will prevent proper ventilation. Most wood-fired hot tubs have a foundation structure made of wood, which tends to get affected by mould, and it can rot fairly quickly. Ensure you avoid this if you are planning on using your spa for more than one or two years. When you’re making such a big investment, no doubt you’ll want to enjoy it for many years to come!
The quickest and cheapest way to avoid this issue with base placement is to prepare your chosen foundation with gravel and then raise your hot tub on concrete slabs or bricks so as to leave the proper gap underneath the hot tub to facilitate the free flow of air for good ventilation.
What is the best base for a wood-fired hot tub?
Concrete, gravel and wooden deck are the top base choices to rest your wood-fired spa on. Each option comes with its own advantages and disadvantages which can be briefly summarised as follows.
| Type of base | Pros | Cons |
|---|---|---|
Concrete Photo credit: Gardenvity | • Extremely sturdy and long-lasting • Inexpensive | • May crack and form puddles or a slope if not installed correctly • Takes a longer time to install |
Concrete slabs or pavement Photo credit: Royal Tubs | • Most sturdy and durable | • Expensive |
Gravel (shingle or pea gravel) Photo credit: The Log Company (Kirami) | • Offers the best drainage • Least expensive • Easiest to install • Will not crack over time | • Cannot guarantee structural integrity over time if placed on relatively soft soil |
Wooden/composite deck Photo credit: Skargards | • Most attractive • Solid and fairly durable | • Most expensive • Requires specialists to install • Requires maintenance to ensure durability |
How heavy is a wood-fired hot tub?
A popular six-person model typically weighs approximately 280 kilograms, and around 2,000 kilograms when filled with water (exceeding the 2-tonne margin fairly easily when occupied by the maximum number of people). The total weight of the hot tub unit depends mainly on the size of the hot tub and the technology features used. For example, if the hot tub features steps, a cover and a water filtration system enclosed in a separate wooden cabinet, this may add some 70-100 kilograms to the weight of the hot tub itself.
Is my deck strong enough for a hot tub?
Construction specialists have commented that, in general, a deck should be able to support approximately 100 pounds per square foot (45 kg per 0.1 m2) if it’s not raised higher than a couple of feet, so it should be perfectly safe to place your wood-fired spa on a deck.
Does a wood-fired hot tub have to be placed perfectly level?
Yes, it does. Any difference in the height of support at the hot tub contact points can cause unwanted structural changes over time. Make sure that each contact point is equally supported so no point is higher or lower than any other point. If the difference in height is visible to the naked eye, the water level at the opposite ends of the hot tub will be unequal too.
Can a hot tub be placed directly on grass?
This would be the worst thing to do. You should not place a wood-fired hot tub on a lawn or soil as it does not provide a solid base. Even slight differences in the height of support at the hot tub contact points can cause unwanted structural changes over time. In addition, when exposed to wet soil and grass, the wooden components can become damaged due to dampness and restricted ventilation, which will eventually promote quicker decay and rotting. Exposure to insects and other pests is also significantly higher when the hot tub is placed on grass, so it should be avoided.
Check your mains connections for your hot tub’s power supply
Wood-fired hot tubs tend to be upgraded with systems that add comfort and ease of use, as well as combined wattage on the electric lines. Therefore, you must make sure to carefully check the requirements with your hot tub manufacturer.
Usually, a wood-fired hot tub with a spa system and water filter will not require any special electric facilities, and you’re good to go with a domestic mains outlet with 13 Amp cabling.
However, with more technology packed into the modern units, you may find yourself using a 2.2 kW hydrotherapy pump, a 700 W air jet compressor and a 3 kW electrical heater working simultaneously (that’s 5.9 kW of combined power). These cannot be plugged into a simple extension cable, and instead will require a stronger supply, which is typically 32 Amp. In such cases, it is essential to consult an authorised electrician to discuss your requirements and the electrical supply in your household. Even so, the power demand for your hot tub will not be as much as what an electric hot tub uses.
Ideally, you should contact the seller and ask about what is required. The next step would be to hire a qualified electrician to install the necessary electrical circuits and switchboard to ensure you comply with all safety requirements.
Preparing the base is all your responsibility
Make no mistake in thinking that a full hot tub installation service includes base preparation too. The reality is that preparing the space in your garden is all your responsibility to arrange. This requires a range of skills and tools to properly set up the spot for your hot tub compared to those involved in installing the tub itself. While some brands do offer a full hot tub installation service (such as Gardenvity and The Log Company), none will prepare the ground for you, so it is important that you do it first.
If you require assistance to prepare that space for your tub and need to hire someone for this, you can check out local contractors and find one who fits your needs.
Non-negotiable steps that can’t be skipped
Before getting a wood-fired hot tub, you must first check whether you live in a Smoke Control Area. If you’re unsure, you can check out this map on the Defra website for assistance. However, Defra also advises you to check with your local council for up to date information, since the data on the map is indicative only. If you live in the UK, you can find your local council here.
We hope that this article has provided you with the information you need to help you choose the right location and base for your wood-fired hot tub. Wishing you happy soaking to come in your new steaming and bubbling wood-fired spa!
